Erosion of rivers, streams, canals, ditches, and other water run-off and irrigation carrying channels is a large and expensive problem in the United States and around the world. Many attempts have been made over hundreds of years at reducing the occurrence of erosion in these channels, but after all these years, these attempts still prove unsatisfactory.
Erosion continues to allow channels to shift, to cross property lines, to undercut roads, railways, and buildings, and even to threaten telephone and electric power transmission lines. Erosion creates large gullies which are difficult to cross, inhibiting travel even when the gullies do not carry water. Erosion also alters the paths of rivers and provides the rivers with new access to flood plains which were previously inaccessible and hence were protected against flooding. Erosion also consumes thousands of acres of prime farm land every year.
As used herein, the term "flow of water" denotes a flow of water in a stream, canal, ditch, creek, lake inlet, pond outlet, or other body of moving water. The term "Channel" collectively denotes the bed over which the flow of water moves and the banks between which the flow of water moves. A channel exists regardless of whether or not it carries a flow of water at any particular time. Although many flows are substantially continuous, as in a large river, other flows such as flash floods are intermittent.
Erosion is caused by the force of the flow of water acting against the channel in which the water flows. The amount of force exerted by the flow of water on the banks and bed of the channel is largely dependent on the velocity of the flow of water. Turmoil in the flow of water can also create eddies which eat away at a particular area of the channel. Over time, due to the force of the flow of water, the soil and other materials of the banks and/or bed of the channel are carried away and redeposited downstream, altering the shape of the channel. In many cases, the altered channel guides the flow of water along a substantially different path than the path that was taken before the erosion occurred.
The speed of erosion is also dependent on many other factors. For instance, rocky channels tend to erode more slowly than channels lined only with soil. The presence of trees and other vegetation along the banks of a channel also tends to slow erosion. On the other hand, erosion occurs quickly in arid or semi-arid regions which have sparse vegetation. These same areas are often subject to flash floods which can severely erode the relatively unprotected channels.
Certain portions of the channels also incur greater erosion than other portions of the channels. For instance, much like any moving body, the flow of water tends to exert greater force on the outside of a curve. This force is embodied as a greater velocity of the flow of water, which in turn deepens the channel bed at the outside of the curve. The deeper channel allows an even greater portion of the flow of water to migrate to the outside of the curve, thereby creating even greater erosion on the outside bank and the outer portion of the channel bed.
Prior art attempts at reducing erosion include the placement of a weir in the channel. A weir resembles a dam in that both obstruct the flow of water. Typically, dam blocks substantially all of the water that reaches it, causing the river to overflow its banks directly upstream of the dam and creating a pond or lake. A weir, on the other hand, slows the flow of water without causing substantial overflow of the banks. The portion of the flow of water around the weir is slowed and flows over the top of or around the weir. Thus, the portion of the flow of water around and immediately downstream of the weir is reduced in velocity, thereby decreasing the force of the flow of water acting upon the channel banks and bed. Thus, erosion is diminished immediately adjacent to and downstream of the weir.
The placement of flow diverters in the channel has also been used in attempts to reduce erosion. Flow diverters typically modify the flow of water by redirecting the flow of water thereof away from locations that are particularly vulnerable to erosion.
Attempts to eliminate erosion have also included the reinforcement of vulnerable portions of the channel bank. Various forms of dikes, levees, walls, old car chassis, and other forms of obstructions have been used for this purpose. As used herein, weirs, flow diverters, and reinforcement barricades will be collectively referred to as flow modifiers.
Prior art flow modifiers have been found generally to be expensive, difficult to install, and not aesthetically pleasing. For instance, the construction of rock jetties and walls is time consuming. The construction of wood barricades can also be expensive, and the barricades are short-lived, as wood tends to rot. The rocks, wood, and other materials are also not readily available in many sites. Additionally, the placement of car chassis in rivers and streams is in some cases unlawful.
Furthermore, most flow modifiers are required to be anchored to the stream bed to prevent the flow modifiers from themselves being washed away. Such anchoring can also be difficult and is often ineffective. For instance, when building wood barricades, large diameter wooden posts must be sunk into the channel bed. This normally requires digging a large hole in the channel bed. Digging in the channel bed proves difficult to do, particularly in a rapidly moving flow of water, and can also make the channel bed more susceptible to erosion. The wooden barricades are also undesirable, as the wooden posts are frequently snapped by sudden rushes of water, causing the barricade to be washed away.
From the above discussion, it can be seen that a need exists for an apparatus, system, and method for modifying the flow of water in a channel that is inexpensive, that is easy to install, and that is sturdy and will not wash out. Such an apparatus, system, and method is also needed which is capable of being installed in the stream in a variety of custom configurations in order to modify the flow of water in the channel and thereby reduce erosion in predetermined portions of the channel.